Observation window washing device of endoscope

ABSTRACT

A notched void portion  29  is provided in a rigid casing block  20  of a rigid tip end section  2   c  of an endoscopic insertion instrument  2.  For spurting a cleaning fluid toward an observation window  11,  a cleaning supply passage is constituted by a cleaner nozzle  13,  a connector pipe  27  and a flexible tube  26.  A cleaner nozzle  13  is partly fitted in the notched void portion  29  which is formed in the rigid casing block  20.  The connector pipe  27  is formed in a staggered shape having an angularly bent intermediate pipe section  27   c  between straight and parallel front and rear pipe sections  27   a  and  27   b.  The straight front pipe section  27   a  is at least partly fitted in the rigid casing block  20  and its fore distal end portion is fitted in the cleaner nozzle  13  over a predetermined length. On the other hand, the flexible tube is fitted on a rear end portion of the straight rear pipe section  27   b  the position of which is offset radially inward relative to the straight front pipe section  27   a  by the angularly bent intermediate pipe section  27   c  to avoid interference with biopsy channel  24,  light guides  24  and wiring cable  17  which are threaded through a foremost angle ring  40  of an angle section  2   b  of the insertion instrument  2.

FIELD OF THE ART

[0001] This invention relates to a device for cleaning an endoscopicobservation window which is provided at a distal end of an elongatedinsertion instrument of a medical endoscope, and more particularly to anendoscopic observation window cleaning device which is particularlysuitable for application to a medical endoscope having a narrowinsertion instrument of a reduced diameter for insertion into a bodycavity.

BACKGROUND OF THE ART

[0002] Generally, endoscopes which are in use in medical fields arelargely composed of a manipulating head assembly to be gripped andmanipulated by an operator, an elongated insertion instrument extendedout on the front side of the manipulating head assembly for insertioninto a body cavity, and a universal cable led out from the manipulatinghead assembly for connecting same to a light source (or to a lightsource and a processor).

[0003] The insertion instrument is provided with at least anillumination window and an observation window on a distal end face. Itis usually the case that the illumination window is provided either atone or two positions on the distal end face. A diffuser lens is fittedin each illumination window in front of a light emitting end of a lightguide which is connected to a light source. On the other hand, anoptical objective lens system is fitted in the observation window, and asolid-state image sensor device is located at the focus of the objectivelens system. Further, an outlet of a biopsy channel is opened in thedistal end face of the insertion instrument. Therefore, when a diseasedportion is spotted as a result of an endoscopic examination, forceps orother biopsy or surgical instruments are passed through the biopsychannel and projected into the body cavity to make a necessarytreatment. Further, the endoscope is provided with the so-calledobservation window cleaning device thereby to spurt a cleaning fluidtoward the observation window in case it is contaminated with bodyfluids or the like. Normally, the observation window cleaning device isprovided on the distal end face of the insertion instrument, and largelycomposed of a jet nozzle for spurting a cleaning fluid, a mixture of acleaning liquid and compressed air, toward the observation window, and acleaning fluid supply passage which supplies the cleaning fluid to thejet nozzle. The cleaning fluid supply passage is extended through theinsertion instrument and into the universal cable via the manipulatinghead assembly.

[0004] A rigid tip end section which is attached to the fore distal endof the insertion instrument is largely constituted by a rigid supportstructure and an insulating cap which is fitted on the distal end of theinsertion instrument. From the standpoint of strength and machinability,the rigid support structure is formed of metallic material and encasedin the insulating cap in such a way as to preclude its exposure to theoutside. The rigid support structure is provided with a predeterminednumber of axial perforations or bores in which the above-mentioned lightguide, optical objective lens system, biopsy channel and jet nozzle areto be fitted.

[0005] For the endoscopic insertion instrument which is introduced intoa body cavity, it is desirable to be as narrow as possible or as smallas possible in outside diameter in order to lessen the pains on the sideof patients. Therefore, various component parts to be fitted in theendoscopic insertion instrument should be compact and small in size aslong as intended functions of these parts are available, and variousattempts have been made in this regard, including layout and positionalrelations of various component parts within the insertion instrument. Asa consequence, the thickness of insertion instruments of recentlydeveloped endoscopes has been reduced almost to a limit. Nevertheless,there is a strong demand for further reductions in diameter ofendoscopic insertion instruments. In addition, to cope withsophistication of endoscopic examinations and treatments or to cope withincreases in functions which are required of an endoscope, there hasbeen a tendency toward incorporating an increased number of componentparts into an endoscopic insertion instrument, for example, in order toprovide two biopsy channels on one endoscopic insertion instrument or toadd a lens drive mechanism to an optical objective lens system in anobservation window for a zooming function. Accordingly, it is importantto position an increased number of required component parts rationallywithin a limited space of a narrow endoscopic insertion instrumentwithout necessitating to increase its outside diameter.

DISCLOSURE OF THE INVENTION

[0006] In view of the foregoing situations, it is an object of thepresent invention to provide an endoscopic observation window cleaningdevice which permits to reduce the outside diameter of a narrowendoscopic insertion instrument further to an extremely small size.

[0007] It is a more particular object of the present invention toprovide an endoscopic observation window cleaning device having acleaner nozzle fitted in position at a distal end of a narrow endoscopicinsertion instrument in such a way as to permit reduction of the outsidediameter of the insertion instrument further to an extremely small size.

[0008] In order to achieve the above-stated objectives, according to thepresent invention, there is provided an endoscopic observation windowcleaning device for an endoscope having an elongated insertioninstrument extended out from a manipulating head assembly, the insertioninstrument having an angle section and a rigid tip end sectionsuccessively connected to a fore end of an elongated flexible body, therigid tip end section having a rigid casing block connected to aforemost one of angle rings of the angle section by fitting engagementtherewith and sheathed in an insulating cap in distal end portionsincluding a distal end face with at least openings for an observationwindow and an illumination window axially in alignment withcorresponding openings in the insulating cap, along with an opening fora cleaner nozzle connected to a cleaning fluid supply passage andarranged to spurt a cleaning fluid toward the observation window, theendoscopic observation window cleaning device comprising: a nozzlefitting portion being axially bored through the rigid casing block ofthe rigid tip end section and having a small diameter portion and aradially spread large diameter portion opened in the distal end face ofthe rigid casing block; a notched void portion being formed in the rigidcasing block laterally on the outer side of the large diameter portionof the nozzle fitting portion in such a way as to form an outermostsegment of the large diameter portion; and a cleaner nozzle fitted inthe large diameter portion of the nozzle fitting portion to form acleaning fluid supply passage along with a connector pipe fitted in thesmall diameter portion of the nozzle fitting portion and connected inthe angle section to a flexible tube from a cleaning fluid supplysource; the cleaner nozzle being fitted in the large diameter portion ofthe nozzle fitting portion and partly in the notched void portion in therigid casing block; and the connector pipe being in a staggered shapehaving an angularly bent intermediate pipe section between straight andparallel front and rear pipe sections and the flexible tube being fittedon the rear pipe section of the connector pipe in the angle section at aposition offset radially inward relative to the front pipe section andfree of interference with other component parts threaded through theangle section.

[0009] The foremost one of angle rings which constitute the anglesection of the insertion instrument is connected to the rigid casingblock of the rigid tip end section. Other angle rings of the anglesection are successively and pivotally connected to the foremost anglering, and various component parts are threaded or fitted internally ofthe angle section. Therefore, there is little space in the angle sectionfor the connector pipe of the cleaning fluid supply passage to beextended and to be connected to the flexible tube which constitutes arear part of the cleaning fluid supply passage. Therefore, it isnecessary and important to control the position of the connector pipe inthe angle section accurately by way of the angularly bent pipe sectionbecause otherwise there will arise the problem of interference withother component parts in the angle section. For this purpose, an indexmark is provided on a rear end face of the rigid casing block toindicate a direction in which the angularly bent intermediate section ofthe connector pipe is to be set. Further, a fore end portion of theconnector pipe is fitted in the cleaner nozzle which is partly fitted inthe notched void portion in the rigid casing block. The notched voidportion is provided in the rigid casing block in such a way as to forman outer segment of a nozzle fitting portion, that is to say, to make anextra space for fitting the cleaner nozzle at the distal end of theendoscopic insertion instrument. Seal material is applied on and aroundouter periphery of the cleaner nozzle in the notched void portion toanchor same in position and to insure air tightness of the insertioninstrument.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the accompanying drawings:

[0011]FIG. 1 is a schematic outer view of an endoscope as a whole,incorporating an embodiment according to the present invention;

[0012]FIG. 2 is a schematic end view of an end face at the fore distalend of an insertion instrument of the endoscope;

[0013]FIG. 3 is a schematic sectional view taken on line X-X of FIG. 2;

[0014]FIG. 4 is a schematic sectional view taken on line Y-Y of FIG. 2;

[0015]FIG. 5 is a schematic sectional view, showing on an enlarged scalemajor component parts which are shown in FIG. 4;

[0016]FIG. 6 is a schematic sectional view taken on line Z-Z of FIG. 3;and

[0017]FIG. 7 is a schematic view of a base end portion of a rigid tipend section of the insertion instrument.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereafter, the present invention is described more particularlyby way of its preferred embodiments with reference to the accompanyingdrawings. Firstly, reference is had to FIG. 1 which shows general layoutof an endoscope. In this figure, indicated at 1 is a manipulating headassembly, at 2 an insertion instrument and at 3 a universal cable of theendoscope. From a proximal end which is connected to the manipulatinghead assembly 1, the endoscopic insertion instrument 2 is successivelycomposed of an elongated flexible body section 2 a, an angle section 2 band a rigid tip end section 2 c. The flexible body section 2 a, which isin the form of a flexible tube structure, is flexibly bendable intoarbitrary directions along curved or bent portions which may exist in apath of insertion into a body cavity. Therefore, a major part of theendoscopic insertion instrument 2 is constituted by the flexible bodysection 2 a. The angle section 2 b can be angularly turned into anupward, downward, rightward or leftward direction by remote control fromthe manipulating head assembly 1. Accordingly, the rigid tip end section2 c can be turned into a desired direction by bending the angle section2 b.

[0019] Schematically shown in FIG. 2 is a distal end face of the rigidtip end section 2 c of the insertion instrument 2. A couple ofillumination windows 10 are provided on the distal end face of the rigidtip end section 2 c (one or three illumination windows are provided insome cases), and an observation window 11 is located at an intermediateposition between the two illumination windows 10. Largely opened underthe observation window 11 is an outlet 12 of a biopsy channel. Further,a cleaner nozzle 13 is provided in the vicinity of the outlet 12 of thebiopsy channel to spurt a wash fluid toward the observation window 11.

[0020] Although not shown in the drawings, a light diffuser lens isfitted in each illumination window 10 in front of a light emitting endof an illumination light guide. On the other hand, as shown in FIG. 3, alens barrel 14 of an optical objective lens system is located behind theobservation window 11. In the case of the particular example which isshown in the drawings, the objective lens system is provided with aprism 15 to turn a light path through 90 degrees to focus picture imageson a solid-state image sensor device 16 which is mounted in a horizontalstate, namely, which is located in a plane parallel with thelongitudinal axis of the insertion instrument 2. Needless to say, theobjective lens system can be arranged to focus picture images on asolid-state image sensor device which is located in a planeperpendicular to the longitudinal axis of the insertion instrument,without bending its light path. Indicated at 17 is a wiring cable whichis connected to the image sensor device 16. The outlet 12 of biopsychannel is provided to protrude forceps or other instruments into a bodycavity whenever necessary for a treatment. From the cleaner nozzle 13, amixture of a cleaning liquid and compressed air is spurted toward theobservation window 11 for cleaning same when contaminated with bodyfluids or the like. Namely, the cleaner nozzle 13 functions to spurt acleaning fluid toward the observation window 11, and constitutes a fluidsupply passage along with a connector pipe 27 and a flexible tube 26which will be described hereinlater.

[0021] The rigid tip end section 2c is constituted by a rigid casingblock 20 consisting of a metal block of substantially columnar shape,and an insulating cap 21 which is fitted on a distal end face of therigid casing block 20. A number of axial bores are formed through therigid casing block 20 for fitting the above-mentioned light guides, lensbarrel of the objective lens system 14, biopsy channel and cleanernozzle 13, in alignment or in communication with openings which areprovided in the insulating cap 21 for the illumination windows,observation window and outlets of the biopsy channel and cleaning fluidpassage, respectively.

[0022]FIG. 3 shows the rigid tip end section 2 c in a longitudinalsection taken through the outlet 12 of the biopsy channel, while FIG. 4shows the same in a longitudinal section taken through the cleanernozzle 13. Indicated at 22 in FIG. 3 is a bore which is formed axiallythrough the rigid casing block 20 to provide an instrument outletpassage 22. The instrument outlet passage 22 is bulged into a largerdiameter at its base end for fitting a connector pipe 23 therein. Inturn, a fore end portion of a biopsy channel 24 which is constituted bya flexible tube is fitted in the connector pipe 23.

[0023] As clear from FIG. 4, a nozzle fitting bore portion 25 isprovided in the rigid casing block 20 of the rigid tip end section.Placed in the nozzle fitting bore portion 25 is a connector pipe 27which is connected to a fore end of a flexible tube 26 of a cleaningfluid supply passage. In order to spurt a cleaning fluid, a mixture of acleaning liquid and compressed air toward the observation window 11, thecleaner nozzle 13 is arranged to turn an axial flow of the cleaningfluid through 90 degrees. For this purpose, the cleaner nozzle 13 iscomposed of an axial tubular body portion 13 a and a spout portion 13 bwhich is turned through 90 degrees from the tubular body portion 13 aand opened toward the observation window 11. In this instance, the spoutportion 13 b is extended along the outer surface of the insulating cap21, while the axial body portion 13 a is extended into an opening 28which is provided in the insulating cap 21.

[0024] The nozzle fitting bore portion 25, mainly consisting of an axialbore which is formed in the rigid casing block 20, is not uniform indiameter but varied stepwise in the longitudinal direction. Namely, thenozzle fitting bore portion 25 is provided with a small diameter portion25 a on the side of its base end, and a large diameter portion 25 bwhich is extended over a predetermined length from its fore distal end.The large diameter portion 25 b of the nozzle fitting bore portion 25 isso positioned as to axially register and align with the outer peripheryof the rigid casing block 20 on the outer side. Therefore, there is nowall of any thickness to cover an outermost segment of the largediameter portion 25 b of the nozzle fitting bore portion 25. Namely, therigid casing block 20 is provided with a notched void portion 29 of apredetermined width on the outer side of the large diameter portion 25 bof the nozzle fitting bore portion 25, permitting to shift the positionof the large diameter portion 25b in a radially outward direction by adistance corresponding to a thickness of a wall which would normallyexist on the outer side of the large diameter portion 25 b. The tubularbody portion 13 a of the cleaner nozzle 13 is fitted in the largediameter portion 25 b of the nozzle fitting portion 25.

[0025] The small diameter portion 25 a of the axial bore whichconstitutes the nozzle fitting portion 25 is formed in a minimumnecessary diameter for fitting the connector pipe 27, while the largediameter portion 25 b is formed in a suitable size for fitting thetubular body portion 13 a of the cleaner nozzle 13. As seen in FIG. 5,the provision of the notched void portion 29 in the rigid casing block20 permits to increase the inside diameter of the nozzle fitting portion25 by utilizing the notched void portion 29 in the rigid casing block aspart of the large diameter portion 25 b for fitting the cleaner nozzle13.

[0026] The rigid casing block 20 which is formed of a metallic materialneeds to be completely shielded in an electrically insulating member.Therefore, the insulating cap 21 is arranged to enshroud the rigidcasing block 20 and constituted by a distal end face 21 a and acircumferential portion 21 b which is fitted on the circumference of therigid casing block 20. The insulating cap 21 is securely fixed to therigid casing block by means of a set screw 30 (see FIG. 2), which iscovered under seal material 31 and thereby retained in an unexposedstate. Proximal end of the circumferential portion 21 b of theinsulating cap 21 is joined with a fore end of an outer skin layer 32 ofsynthetic resin, rubber or other electrically insulating material, whichis extended from the side of the angle section 2b and fixedly anchoredin position by line wrapping 33. An adhesive 34 is applied across themeeting ends of the outer skin layer 32 and the insulating cap 21 andaround the line wrapping 33 to fix the outer skin layer 32 and tohermetically seal the joint portion of the outer skin layer 32 and theinsulating cap 21.

[0027] In this instance, as clear from FIG. 2, it is desirable toprovide a certain degree of diametrical differential between the outsidediameter of the rigid casing block 20 and the inside diameter of thecircumferential portion 21 b of the insulating cap 21 so that theinsulating cap 21 is loosely fitted around the rigid casing block 20.With such a diametrical differential, it becomes easier to fit theinsulating cap 21 on the rigid casing block 20 even if openings in thedistal end face 21 a are arranged to tightly and substantiallyhermetically fit on the illumination windows 10, the observation window11 etc. In this instance, it is desirable to fill seal material in a gapspace which may exists between the rigid casing block 20 and theinsulating cap 21. However, there is no necessity for filling a gapspace between the rigid casing block 20 and the insulating cap 21completely with seal material because a hermetical seal is formed by theadhesive 34 which is applied around and across meeting ends of the outerskin layer 34 and the circumferential portion 21 b of the insulating cap21 as described hereinbefore.

[0028] The nozzle 13 which is projected on the outer side of the foredistal end of the rigid tip end section 2 c is formed of a suitablematerial in electrically insulating properties, more specifically,formed of hard plastics or synthetic resin material. In this regard, thecleaner nozzle 13 needs to have a wall thickness markedly greater thanthe connector pipe 27 because plastic material is inferior to a metalpipe in strength, for example, a wall thickness several times as largeas that of the connector pipe 27. Namely, as compared with the outsidediameter of the tubular body portion 13 a of the cleaner nozzle 13, theoutside diameter of the connector pipe 27 which constitutes part of thecleaning fluid supply passage can be reduced to a sufficient degree forplacement in the small diameter portion 25 a of the nozzle fittingportion 25 in the rigid casing block 20.

[0029] On the other hand, the tubular body portion 13 a of the cleanernozzle 13 which is located at the fore distal end of the rigid casingblock 20 is partly fitted in the latter and is relatively short in axiallength. Taking these points into consideration, as shown particularly inFIG. 5, the nozzle fitting portion 25 on the rigid casing block 20 isprovided with the large diameter portion 25 b of a predetermined lengthL from its fore distal end, and a notched void portion 29 is provided inthe rigid casing block 20 immediately on the outer side of the largediameter portion 25 b to utilize the notched void portion as part of thelarge diameter portion in securing a sufficiently large diameter D₂ forfitting the cleaner nozzle 13 on the front side of the narrow smalldiameter portion 25 a with a far smaller diameter D₁. Thus, theprovision of the notched void portion 29 makes it possible to fit thecleaner nozzle 13 into a limited narrow space despite its large wallthickness as compared with the connector pipe 27, locating an outerlateral side of the tubular body portion 13 a of the cleaner nozzle 13substantially flush with the outer periphery of the rigid casing block20 in the axial direction. In this manner, the shift of the cleanernozzle fitting portion to a notched void portion which is provided atone lateral side of the rigid casing block 20 permits to reduce theoutside diameter of the rigid casing block 20 as compared with a case inwhich the nozzle fitting portion is bored completely through and withinthe rigid casing block 20. Namely, it becomes possible to reduce thediameter of the endoscopic insertion instrument 2 itself. Besides, theshift of the cleaner nozzle 13 to one lateral side of the insertioninstrument contributes to make an extra room or space in or in thevicinity of central areas of the rigid casing block 20, which will givea greater degree of freedom in laying out other component parts to beincorporated into the insertion instrument 2.

[0030] The tubular body 13 a of the cleaner nozzle 13 which is fitted inthe large diameter portion 25 b of the nozzle fitting bore 25 is alsopartly fitted in the notched void portion 29 to have its outer endsubstantially flush with the outer periphery of the rigid casing block20, and enshrouded in the circumferential portion 21 b of the insulatingcap 21 along with the rigid casing block 20. The connector pipe 27 whichis fitted in the small diameter portion 25 a is extended rearward of theproximal end of the rigid casing block and into the angle section 2 band fitted in a flexible tube 26. The angle section 2 b is provided withangle rings 40 as structural units. As well known in the art, the anglesection 2 b is constituted by a plural number of angle rings 40 whichare pivotally connected in series alternately by way of vertical andhorizontal joints, and is angularly bendable in four directions bypulling paired operating wires either in a forward or backwarddirection. Therefore, if the connector pipe 27 is extended into theangle section 2 b in a straight form, there will be almost no gap spacebetween the connector pipe 27 and the angle ring 40 which will permit tofit the flexible tube 26 on the connector pipe 27, and there may arise aproblem of interference with the angle section operating wires or othercomponent parts which are threaded through the angle section 2 b.

[0031] In order to avoid the problems as mentioned above, the connectorpipe 27 is bent into a staggered shape having an angularly bentintermediate pipe section 27 c between straight front and rear pipesections 27 a and 27 b to offset the rear section 27 b radially inwardof the front section 27 a in parallel relation with the latter. Thestraight front section 27 a is placed in the nozzle fitting portion 25in the rigid casing block 20, while the straight rear section 27 b isfitted in the flexible tube 26. Thus, relative to the straight frontsection 27 a, the straight rear section 27 b is offset radially inwardby a distance Δf (see FIG. 4). The rear section 27 b of the connectorpipe 27 is spaced apart from the inner periphery of the angle ring 40 tomake a room or a gap space for fitting the flexible tube 26 thereon.

[0032] In the case of the particular embodiment shown, the biopsychannel 24, light guides 41 and wiring cable 17 from the image sensormeans 16 are passed through the angle section 2 b of the insertioninstrument 2 as seen in FIG. 6, along with a control cable 42 serving asa lens drive means for the optical objective lens system, and fouroperating wires 43 for bending the angle section 2 b, i.e., a pair ofupper and lower operating wires and a pair of right and left operatingwires, for bending the angle section 2 b by remote control from themanipulating head assembly. Therefore, the flexible tube 26 whichconstitutes a fluid supply passage should be located not only in aposition which is spaced from the inner periphery of the angle ring 40but also in a position precisely intermediate between the control cable42 and the operating wires 43. This means that, at the time of fittingthe connector pipe 27, it is necessary and important to control thedirection of the bent section 27 c of the connector pipe 27 correctly.

[0033] As shown in FIG. 7, in order to correctly control the directionof the angularly bent section 27 c of the connector pipe 27, an indexmark 44 is provided on a rear end face of the rigid casing block 20 toindicate the direction in which the angularly bent pipe section 2 cshould be set. The index mark 44 may be a color mark but, from thestandpoint of stability and durability as a directional index, it ispreferable to form a notch, groove, rib or ridge-like protuberance onthe rear end face of the rigid casing block. Thus, by turning theconnector pipe 27 into the direction of the index mark 44 after placingthe straight front pipe section 27 a in the nozzle fitting portion 25,the straight rear pipe section 27 b of the connector pipe can be set inposition within the angle section 2 b, free of interferences with othercomponent parts which are passed through the angle section 2 b.Accordingly, it becomes possible to make adjustments so that theflexible tube 26 can be easily fitted on the straight pipe section 27 b.In FIG. 7, indicated at 45 is a set screw which fixes the cleaner nozzle13 in position.

[0034] In this instance, after placing the connector pipe 27 into thetubular body portion 13 a of the cleaner nozzle 13 over a predeterminedfitting length, seal material 35 is is applied around the rear end ofthe tubular body 13 a to fill in the gap space between these two parts.The applied seal material 35 contributes to anchor the cleaner nozzle 13in position, to improve air tightness of the insertion instrument 2 andto preclude irregular variations in outside diameter. Besides, since afore end portion of the connector pipe 27 is placed in the tubular bodyportion 13 a of the cleaner nozzle 13 over a substantial length, thereis no possibilities of the applied seal material 35 getting into thecleaning fluid supply passage within the connector pipe 27 and thecleaner nozzle 13. Therefore, if desired, the inside diameter of thecleaner nozzle 13 may be appreciably differentiated from the outsidediameter of the connector pipe 27 for the purpose of facilitating theirfitting engagement. Further, an adhesive 46 is applied around the outerperiphery of a transitional nozzle portion between the tubular bodyportion 13 a and the spout portion 13 b of the cleaner nozzle 13 therebyto securely anchor the cleaner nozzle 13 in position and at the sametime to insure air tightness of the insertion instrument 2.

[0035] In the foregoing preferred embodiment, it has been described thatthe whole cleaner nozzle 13 is formed of a synthetic resin material orplastics. However, it may be formed of a metallic material as long as itis electrically insulated from the rigid casing block 20. In the case ofa metallic cleaner nozzle, it is desirable to fit an insulating sleeveon the outer periphery of the tubular body portion of the cleanernozzle. In such a case, however, the outside of the cleaner nozzle isinevitably increased by addition of an insulating sleeve. Nevertheless,the outside diameter of an endoscopic insertion instrument can bereduced to a minimum size by locating the insulating sleeve within anotched void portion 29 which is formed in a rigid casing block of arigid tip end section of the insertion instrument.

What is claimed is:
 1. An endoscopic observation window cleaning devicefor an endoscope having an elongated insertion instrument extended outfrom a manipulating head assembly, said insertion instrument having anangle section and a rigid tip end section successively connected to afore end of an elongated flexible body, said rigid tip end sectionhaving a rigid casing block connected to a foremost one of angle ringsof said angle section by fitting engagement therewith and sheathed in aninsulating cap in distal end portions including a distal end face withat least openings for observation and illumination windows axially inalignment with corresponding openings in said insulating cap, along withan opening for a cleaner nozzle connected to a cleaning fluid supplypassage and arranged to spurt a cleaning fluid toward said observationwindow, said endoscopic observation window cleaning device comprising: anozzle fitting portion being axially bored through said rigid casingblock of said rigid tip end section and having a small diameter portionand a radially spread large diameter portion opened in said distal endface of said rigid casing block; a notched void portion being formed insaid rigid casing block laterally on the outer side of said largediameter portion of said nozzle fitting portion in such a way as to forman outermost segment of said large diameter portion; and a cleanernozzle fitted in said large diameter portion of said nozzle fittingportion to form a cleaning fluid supply passage along with a connectorpipe fitted in said small diameter portion of said nozzle fittingportion and connected in said angle section to a flexible tube from acleaning fluid supply source; said cleaner nozzle being fitted in saidlarge diameter portion of said nozzle fitting portion and partly in saidnotched void portion in said rigid casing block; and said connector pipebeing in a staggered shape having an angularly bent intermediate pipesection between straight and parallel front and rear pipe sections andsaid flexible tube being fitted on said rear pipe section of saidconnector pipe in said angle section at a position offset radiallyinward relative to said front pipe section and free of interference withother component parts threaded through said angle section.
 2. Anendoscopic observation window cleaning device as defined in claim 1,wherein said large diameter portion of said nozzle fitting portion islocated to have said outer segment substantially flush with outerperiphery of said rigid casing block, and said notched void portion isformed to have a radial width containing an outer segment of both saidlarge diameter portion and said rigid casing block.
 3. An endoscopicobservation window cleaning device as defined in claim 1, wherein saidrigid casing block is provided with an index mark on a rear end facethereof to indicate a direction in which said angularly bentintermediate pipe section is to be set within said angle section of saidinsertion instrument.
 4. An endoscopic observation window cleaningdevice as defined in claim 1, wherein a seal material is applied aroundouter peripheral portions in said notched void portion of said rigidcasing block.